Six diabetic Pima Indians who were not receiving either oral hypoglycemics or insulin were kept in a hyperglycemic state. Metabolic parameters of biliary lipid cholesterol composition and total body cholesterol balance were investigated in this hyperglycemic state. Upon completion the patients were treated for their diabetes with insulin. The repeat studies of biliary cholesterol composition and body cholesterol production were investigated in the euglycemic state. Biliary cholesterol composition and body cholesterol production were determined by previously published methods. The preliminary data at this stage suggests that the synthesis of cholesterol is increased in the uncontrolled diabetic state as compared to the euglycemic state. Bile acid pool size is expanded resulting in decreased saturation of bile with cholesterol. It is proposed that cholesterol synthesis may be increased in the diabetic hyperglycemic state, which may provide an explanation for the increase in atherosclerosis among diabetics.